The Datcon 71076-00 Tachometer Gauge is an English-Metric gauge that uses the same rugged platform as our HDI (Heavy Duty Industrial) line, and feature well-known orange-white graphics for an improved operator interface. This tachometer gauge operates at 12/24 volts and gets its signal source from alternator. It also features a scale range of 0-4000 RPM and a gauge diameter of 3 3/8 inches.